Efficacy of some chemicals and bioinsecticides against cotton mealybug Phenacoccus solenopsis (Hemiptera: Pseudococcidae) as a new recorded pest of sugar beet in Egypt

Abstract

Abstract The purpose of this study was to evaluate the effectiveness of chemical and bioinsecticides against the cotton mealybug Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae), which was recently found infesting sugar beet (Beta vulgaris L.) in Egypt. Lambda-cyhalothrin, mineral oil, sulfoxaflor, and Biossiana® are some of the chemical and bioinsecticides that are commonly used. Field trials were conducted over two consecutive growing seasons (2022–2023) in Kafr El-Sheikh Governorate using a randomized complete block design. Results demonstrated that lambda-cyhalothrin and sulfoxaflor achieved the highest population reductions (99.92% and 99.31%, respectively), with rapid knockdown effects attributed to their neurotoxic modes of action. Mineral oil showed delayed but significant efficacy (98.4% reduction by day 10), consistent with its physical mode of action. The biofungicide Biossiana® exhibited progressive control (96.1–99.31% reduction), with its performance linked to wax degradation and cuticular penetration. The study demonstrated that the efficacy of control measures against P. solenopsis was substantially influenced by the pest's distinctive morphological adaptations, most notably its protective wax coating and cryptic feeding behavior. These biological traits underscore the importance of adopting integrated pest management strategies that combine chemical and biological control methods. To optimize management outcomes, applications should be timed to coincide with vulnerable life stages, while treatment combinations should be employed to counteract the pest's wax-mediated resistance mechanisms. Furthermore, regular rotation of control agents is essential to maintain long-term effectiveness. This research aimed to provide crucial insights for developing sustainable management approaches against this recent pest infested sugar beet, offering solutions that balance effective control with environmental conservation.